1. Field of the Invention
The present invention relates generally to automotive vehicle light signaling systems, and more particularly to an arrangement in which an amber/yellow warning lamp associated with a center-mounted red brake lamp is energized continuously, except when the vehicle brakes are activated at which time the amber/yellow lamp is extinguished and the brake lamp is energized.
2. Description of the Known Art
Rear signal light warning systems employing a combination of red, amber and green lamps are known from U.S. Pat. Nos. 2,760,113 (Aug. 21, 1985) and 3,676,844 (July 11, 1972). The '113 patent disclosed a signal light housing suspended near the rear window of a vehicle and containing individual red, amber and green signal lights. The red light is wired to be energized simultaneously with the standard stop lights of the vehicle, i.e., when a brake operated stop light switch is closed. During acceleration of the vehicle, the green light is illuminated to signal a driver of a following vehicle accordingly. Only when the driver of a leading vehicle removes his or her foot from the accelerator without application of the brakes (i.e., the vehicle is coasting) the amber signal light is illuminated. The '844 patent shows, in FIG. 2b, an arrangement of red, green, and amber signal lights extending horizontally below the rear deck of a vehicle. As in the arrangement of the '113 patent, the amber lights are energized in a coasting condition, and a central green light is illuminated when the vehicle is accelerating.
U.S. Pat. No. 4,600,913 issued July 15, 1986 to the present inventor disclosed a collision avoidance device including a single housing mounted centrally on the rear of a leading vehicle and containing a brake light and a safe distance signal light. Operation of the safe distance signal light is, however, independent of energization of the brake light. The intensity of the signal light can be varied in accordance with the ambient light by way of a photoelectric device.
According to U.S. Department of Transportation statistics, rear-end collisions accounted for about 30% of automobile accidents in the United States in 1986. The severity of this problem resulted in the mandating of the installation of high-mounted brake lights on all 1986 model automobiles in the United States.
Reduction in the number of rear-end automobile collisions can be obtained only through means of insuring that drivers maintain safer headways. That is, a driver of a following vehicle must maintain a sufficient distance between his car and a car directly in front such that he can safely stop his vehicle after a panic stop by the leading driver. Thus, the intervening distance must be maintained sufficient for the following driver to have time to (1) perceive, (2) respond, and (3) decelerate, regardless of the leading vehicle's rate of deceleration and without colliding with the vehicle.
The effectiveness of the center high-mounted brake light lies in its placement in the following driver's field of view. Dual brake lights mounted at the same height but to either side of the central visual field were found in tests to be less effective. Thus, a centrally mounted lamp facilitates perception of the brake light and reduces response time. Controlled studies with instrumented vehicles have shown that the center high-mounted brake light reduces the time between leading vehicle brake light onset and following vehicle brake application, by approximately 25%.
The center, high-mounted brake light begins to serve as an accident countermeasure when one vehicle trails another so closely that a difference in response time of 25%, that is between 0.3 and 0.4 seconds is sufficient to have a significant effect on the probability of avoiding a collision. Further reductions in rear-end collisions may be achieved if vehicle spacing is increased by an amount sufficient so that there is ample time to respond to braking by the leading vehicle, and response time of the driver of the following vehicle does not become a critical factor. An early attempt to enhance the rearward conspicuity of automotive vehicles so as to promote increased spacing, has been the use of tail lights. Of course, conventional tail lights are illuminated continuously only during night time driving and, until now, the use of easily perceived rear lighting to enhance daytime conspicuity of vehicles from the rear, as a running light has not been studied systematically.